The present invention is particularly related to a rotary roller set directional control device suitable for directional roller displacement of a rotary roller set at the bottom of portable handcart such as the baby carriage and shopping cart. An annular flange is on the top edge of a pivotal shaft socket to lower its frictional resistance, and an elastic element and a positioning column are in a long shaft hole on the rear end of roller seat. The positioning column moves therein and through the buffer force of the elastic element maintains the smooth and stable movement forward of the handcart. This controls the pivotal shaft socket making its direction stable and to making its directional change easy as well as making shockproof.
The conventional baby carriage, shopping cart or portable handcart is provided with a plurality of roller sets at its bottom which may be fixed or rotary. The fixed set can move or roll in a certain direction, and the rotary one set can move in any chosen direction for 360.degree. in line with the rotary shaft of roller set. Namely, when pushing the handcart, one has only to apply a force to the handcart in the desirable direction, and the rotary roller set can rotate and roll forward accordingly.
This conventional rotary roller set can roll in any direction, but its direction has to be fixed if directional movement, is necessary so a directional device is provided to the rotary roller set as a rule. So far as the conventional directional device is concerned, an annular member is inserted in the pivotal shaft socket thru the pivotal supporting arm of rotary roller set. Since there is a considerable gap between the annular member and the pivotal shaft socket, the rotary roller set is susbject to resistance when rolling and moving the roller will then slip out of its position, and the roller set will move in an undesirable direction. This drawback is always found in the front wheels of baby carriage. However, if the pivotal supporting arm is in tight contact with the pivotal shaft socket, since the contact area is large it generates a high frictional coefficient and it is difficult to rotate the pivotal shaft socket for movement when rotating the U-shaped rocker of rotary roller set for directional regulation. In the circumstances, the said frictional resistance has to be lowered so as to enhance the rotary efficiency thereof. However, no buffer mechanism is provided to the rotary roller set, in case of moving on a rough road, the handcart per se will drastically jolt. If the baby carriage moves thereon, the baby will never be able to peacefully fall asleep in the carriage or might get be hurt from collision with the carriage per se. So the prohibitive jolt and shock of rotary roller set in the course of moving on a rough road should be improved.
Under the effect of artifical factors of poor design of conventional rotary roller set directional control device, the prohibitive drawback the handcart cannot achieve the purpose of safety and comfort. Therefore, an improved rotary roller set directional control device has to be developed.